Work stripping mechanism for punch press die



och 1965 Li H. BuczKowsKE WORK STRIPPING MECHANISM FOR PUNCH PRESS DIE 2 Sheets-Sheet 1 Filed April 3, 1963 INVENTOR Lao H BuczKowsKE BY t l WI ATTORNEYj Oct. 5, 1965 L. H. BuczKowsKE WORK STRIPPING MECHANISM FOR PUNCH PRESS DIE 2 Sheets-Sheet 2 Filed April 3, 1963 INVENTOR Leo H BUCZKOUJSKE BY W 1 101m iTTORNEYS m WHH United States Patent 3,209,631 WURK STRIPIING MEUHANISM FUR PUNCH PRESS DIE lLeo H. Buczkowske, Chicago, Ill., assignor to Continental Can Company, Inc, New York, N.Y., a corporation of New York Filed Apr. 3, 1963, Ser. No. 270,383 19 Claims. (6]. 83-131) This invention relates to a new and useful improvement in punch press constructions, and more particularly is concerned with providing a work stripping mechanism for a punch press die.

A primary object of the invention is to provide apparatus for removing a work piece from a punch of a punch press after a punching operation has been completed.

Another object of this invention is to provide apparatus for stripping the work piece off the punch during a return stroke of the punch.

A further object of this invention is to provide the punch with a spring-1oaded stripper ring for removing the work piece from the punch.

A further object of this invention is to provide springbiased toggle-links for selectively locking the stripper ring to and unlocking the stripper ring from the punch.

Another object of this invention is to provide a novel knockout stem which is slidably mounted in a punch holder of a punch press and is spring-loaded to provide for relative movement between the knockout stem and the punch holder.

A further object of this invention is to provide the novel knockout stem with pivotally mounted toggle-links for selectively locking and unlocking the stripper ring to and from the punch.

It is a further object of this invention is provide a lostmotion connection between the stripper ring and the punch holder such that the stripper ring is movable relative to the punch holder and the punch.

Another object of this invention is to provide a knockout bar disposed in the path of movement of the knockout stem so that the knockout stem is held stationary during part of the travel of the punch holder and the punch.

A still further object of this invention is to provide abutment pins on the punch which are engageable with the pivoted toggle-links to unlock the toggle-links from the spring-loaded stripper ring so that the stripper ring is moved relative to the punch to strip the work piece from the punch.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claimed subject matter and the several views illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a plan View of a punch press and shows a punch holder mounted for vertical reciprocatory sliding movement on a pair of guide posts, and a portion of a conventional die shoe having bifurcated lug portions for attaching the die shoe to a work station.

FIGURE 2 is a vertical sectional view taken generally on line 2 2 of FIGURE 1 and shows a spring-loaded stripper ring mounted for sliding movement on a punch and having a lost motion connection with the punch holder, and a knockout stem having spring-biased togglelocks pivoted to one end of the stem and being shown in the position where the stripper ring is locked relative to the punch.

FIGURE 3 is a schematic fragmentary sectional view similar to FIGURE 2 and shows a knockout bar disposed above the punch holder with the punch holder being "ice shown spaced above the die shoe during an upward stroke of the punch holder and punch.

FIGURE 4 is a schematic fragmentary sectional view similar to FIGURES 2 and 3 and shows the knockout stem in abutting relation with the knockout bar and the toggle-locks in the unlocked position with the stripper ring being spring-biased to project below the punch to strip a work piece from frictional engagement with the punch.

FIGURE 5 is a schematic fragmentary sectional view similar to FIGURES 2, 3 and 4 and shows the punch as it comes into contact with the next work piece to be operated upon and shows the toggle-locks just prior to relocking of the stripper ring with the punch, and the punch holder is shown slightly above its lowermost position.

Referring now to the drawings in detail, there is shown in FIGURES 1 and 2 a portion of a punch press, generally referred to by the numeral 10, comprising a die shoe 11 and a punch holder 12 which are retained in operational relationship by a pair of leader pins or guide posts 13.

The guide posts 13 are fixedly mounted in a bore 14 in the die shoe 11 and a pair of sleeve members 15 are each fixedly mounted in a bore 16 in the punch holder 12. Each sleeve member 15 slides on a respective guide post 13 and maintains the punch holder 12 in alignment with the die shoe 11.

The die shoe 11 has mounting lugs 17 for receiving bolts (not shown) for immovably fastening the die shoe 11 on a conventional punch press base (not shown). A fixed shear member 18 is centrally disposed on the upper surface of the die shoe l1 and is fastened thereto by bolts 19. The fixed shear member 18 carries a locating ring 20 which is removably secured to the shear member 18 by screws 21.

A work piece 22 is properly positioned by the locating ring 20 in relation to a vertically reciprocable punch 23 which coacts with a cutting-edge 24 on the shear member 18 for blanking out a hole in the work piece 22. The blanked out piece (not shown) is discharged through a passage 25 in the shear member 18 and an aligned passage 26 in the die shoe 11.

The punch 23 is fastened to the punch holder 12 by screws 27 and has a stripper ring 30 slidably disposed thereon. The stripper ring 30 is attached to the punch holder 12 by bolts 31 that extend through openings 32 in the stripper ring 30 and have lost motion connections therewith. The stripper ring 30 is normally biased downwardly away from the punch holder 12 by four stripper springs 33 which are disposed in recesses 34 in the punch holder 12 and are held in alignment by guide pins 35 which are carried by the stripper ring 34 A knockout stem 4% is slidably disposed in the punch holder I2 and extends into a transverse groove or slot 41 in the punch 23. A compression spring 42 is mounted on the knockout stem and is disposed in a recess 43 of the punch holder 12 and is held in position by an adjustment nut 44 and a lock nut 45.

A pair of oppositely extending toggle-links 46 are disposed in the slot 41 and are pivotally connected at their inner ends to the lower end of the knockout stem 40 by a transverse pivot pin 47. Each toggle-link 46 has a rounded outer nose end 48 which is receivable in one of a pair of shallow locking recesses 49 in the inner surface of the stripper ring 30. The lower surfaces of the outer end portions of the toggle links 46 are yieldingly retained in engagement with abutment pins 50 which are fixedly mounted in the punch 23. A rectangular washer 51 is slidably disposed on the knockout stem 40 and is biased against the toggle-links 46 by a spring 52 which abuts against a collar 53 which is fixed to the knockout stem 40.

From the foregoing description of the various elements and a consideration of the various positions of the device as is shown in FIGURES 25, the operation of the apparatus will be readily understood.

In FIGURE 2 the apparatus is shown in its lowermost position just subsequent to a punching operation. The punch 23 is below the cutting edge 24 and is disposed in the passage 25. Toggle-links 46 have their nose ends 48 disposed in the recesses 49 and are held against the abutment pins 50 by the washer 51 and the spring 52. The springs 33 are held in compression and the stripper ring 30 is spaced upwardly from the lower end of the bolts 31 with the stripper ring 30 being locked to the punch holder 12 by the toggle-links 46 for movement with the punch 23.

The punch holder 12 is now moved upwardly to the position of FIGURE 3 by vertically reciprocating power means which are not shown but may be of any suitable type known in the punch press art. As is shown in FIG- URE 3, the lock nut 45 on the knockout stem 40 approaches a knockout bar 60 which is permanently positioned in the punch press 10. The work piece 22 is in frictional contact with the punch 23 and is engaged with the lower surface of the stripper ring 30 which is still locked relative to the punch holder 12 and the punch 23 for movement therewith.

In FIGURE 4 the apparatus is shown just after the lock nut 45 on the knockout stem 40 has contacted the knockout bar 69. The punch holder 12 continues its upward movement and carries the punch 23 therewith since these elements are fixed together by the screws 27, as was previously described. The continued movement of the I punch 23 relative to the knockout stem causes the abutment pins to pivot the toggle links 46 about the pivot pin 47 and against the resistance of the spring 52 and to move the nose ends 48 of the toggle links 46 out of the recesses 49 in the stripper ring 30. The stripper springs 33 which were being held in compression due to the locking of the stripper ring 30 to the punch holder 12 now expand and force the stripper ring 39 downwardly relative to the punch 23 and strips the Work piece 22 therefrom.

At this stage of the operation the finished work piece 22 is removed from the press 10 and a blank B (as is shown in FIGURE 5) is positioned in the locating ring 20 in preparation for the next sequence of operations of the punch press.

The punch holder 12 moves downwardly accompanied by a like movement of the stripper ring 30 until the lower surface of the stripper ring 30 comes into contact with the blank 13 and is prevented from any further downward movement thereby. The punch 23 and punch holder 12 continue to move further downwardly and the punch holder 12 begins to recompress the stripper springs 33. As these springs 33 bear against the stripper ring 30, the blank B is held in pressing engagement with the shear member 18.

The collar 53, as shown in FIGURE 5, has been reengaged with the lower surface of the punch holder 12 by the expansion of the spring 42 as the knockout stem 40 moves downward away from the knockout bar 60. The stripper ring 30 engages the blank B and seats the blank in the locating ring 20 in preparation for the next blanking operation. The nose ends 48 of the togglelinks 46 lie in grooves 61 in the top edge of the stripper ring 30. Continued downward movement of the punch holder 12 and the punch 23 coupled with the now stationary stripper ring 30, causes the toggle-links 46 to pivot about pin 47 against the spring 52. The nose ends 48 of the toggle-links 46 are carried past the groove 61 and the spring 52 expands and holds the nose ends 48 into the recesses 49 of the stripper ring, as shown in FIGURE 2, thus completing the sequence of operation.

While only a preferred form of the stripper ring and the associated parts has been shown in illustrating the invention, it is to be clearly understood that such showing is only exemplary and various changes in the details and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A stripping mechanism for a punch press having a fixed shear member and a reciprocable punch comprising; a stripper ring, means for mounting said stripper ring for relative movement on said punch; means for selectively locking said stripper ring to said punch; and means for moving said stripper ring relative to said punch; said lock means comprising a knockout stem, toggle-link means carried by said knockout stem, recess means provided in said stripper ring for receiving said toggle-link means therein, resilient means carried by said knockout stem for biasing said toggle'link means into said recess means, and means on said punch being engageable with said toggle-link means for moving said toggle-link means out of said recess means.

2. Apparatus for stripping a work piece from a reciprocable punch of a punch press comprising; a stripper ring mounted for relative movement on said punch, lock means for selectively locking said stripper ring to said punch, lost motion connection means connecting said stripper ring to said punch, and means for moving said stripper ring relative to said punch; said lock means comprising a knockout stem, toggle-link means carried by said knockout stem, recess means provided in said stripper ring for receiving said toggle-link means therein, resilient means carried by said knockout stern for biasing said toggle-link means into said recess means, and means on said punch being engageable with said toggle-link means for moving said toggle-link means out of said recess means.

3. In combination with a punch holder for a punch press, a punch fixedly connected to said punch holder, a stripper ring disposed about said punch and slidable thereon; 10st motion connecting means connecting said stripper ring to said punch holder and providing for relative movement therebetween; resilient means engaging said stripper ring and said punch holder for separating said stripper ring and said punch holder; and lock means for fixing said stripper ring relative to said punch holder.

4. In combination with a punch holder for a punch press, a punch fixedly connected to said punch holder, and abutment means on said punch; a stripper ring disposed about said punch and slidable thereon; lost motion connecting means connecting said stripper ring to said punch holder and providing for relative movement therebetween; resilient means for separating said stripper ring and said punch holder; a knock-out stem slidably mounted in said punch holder, toggle-link means pivotally mounted on one end of said knock-out stem, spring means on said knockout stem in engagement with and biasing said toggle-link means against .said abutment means, and recess means provided in said stripper ring for receiving said toggle-link means.

5. The combination of claim 4 wherein said punch has a transverse groove therein, said abutment means on said punch being disposed within said groove.

6. A stripping mechanism for a reciprocating punch comprising a stripper member mounted for movement relative to said punch to efiect a punch tripping operation, means norm-ally urging said Stripper member to a punch stripping position, and means for automatically temporarily locking said stripper member relative to said punch at the conclusion of a punching operation to delay the punch stripping operation of said stripper member, said stripper member locking means including spring biased toggle-links connected to said punch and having a nose end disposable within a recess formed in said stripper member.

7. A stripping mechanism for a reciprocating punch comprising a stripper member mounted for movement relative to said punch to effect a punch stripping operation, means normally urging said stripper member to a punch stripping position, and means for automatically temporarily locking said stripper member relative to said punch at the conclusion of a punching operation to delay the punch stripping operation of said stripper member, said stripper member locking means including spring biased toggle-links connected to said punch and having a nose end disposable Within a recess formed in said stripper member, said toggle-links being pivotally supported on a support member normally fixed relative to said punch and being movable relative to said punch to effect the releasing of said stripper member from said togglelinks by forcing said nose end out of said recess.

8. The stripping mechanism of claim 7 together with a toggle-link releasing member positioned for engagement by said support member after a predetermined return movement of said punch.

9. The stripping mechanism of claim 7 together with abutment means carried by said punch engageable with said toggle-links and cooperable with said support member upon movement of said support member to pivot said toggle-links to a stripper member releasing position.

6 10. The stripping mechanism of claim 7 together With a toggle-link releasing member positioned for engagement by said support member after a predetermined return movement of said punch, abutment means carried by said punch engageable With said toggle-links and cooperable with said support member upon movement of said support member to pivot said toggle-links to a strip per member releasing position.

References Cited by the Examiner UNITED STATES PATENTS 706,279 8/02 Temple 83131 1,305,766 6/19 Bullard 83131 2,196,209 4/40 Glunz 83146 X 3,033,065 5/62 Fuller 83-136 X 3,119,293 1/64 Allen et al 83-131 FOREIGN PATENTS 178,075 9/22 Great Britain.

82,476 10/ 19 Switzerland.

ANDREW R. JUHASZ, Primary Examiner. 

1. A STRIPPING MECHANISM FOR A PUNCH PRESS HAVING A FIXED SHEAR MEMBER AND A RECIPROCABLE PUNCH COMPRISING; A STRIPPER RING, MEANS FOR MOUNTING SAID STRIPPER RING FOR RELATIVE MOVEMENT ON SAID PUNCH; MEANS FOR SELECTIVELY LOCKING SAID STRIPPER RING TO SAID PUNCH; AND MEANS FOR MOVING SAID STRIPPER RING RELATIVE TO SAID PUNCH; SAID LOCK MEANS COMPRISING A KNOCKOUT STEM, RECESS MEANS PROVIDED IN SAID STRIPPER RING FOR RECEIVING SAID TOGGLE-LINK VIDED IN SAID STRIPPER RING FOR RECEIVING SAID TOGGLE-LINK MEANS THEREIN, RESILIENT MEANS CARRIED BY SAID KNOCKOUT STEM FOR BIASING SAID TOGGLE-LINK MEANS INTO SAID RECESS MEANS, AND MEANS ON SAID PUNCH BEING ENGAGEABLE WITH SAID TOGGLE-LINK MEANS FOR MOVING SAID TOGGLE-LINK MEANS OUT OF SAID RECESS MEANS. 